Black holes are small, yet amazingly powerful ethereal bodies in outer space. A black hole comes from the remains of a massive star collapsing in on its self, and when it does this, what was once an extremely large star, taking up space in the magnitude of several times larger than the Sun of our own Solar System, into a sphere that is roughly the size of a small town. The result of this massive amount of matter being compressed into a not so massive area of space creates a field of gravity that is so strong, that it sucks up everything that enters it. Even light, an energy that is heralded far and wide as being the fastest bit of matter in the galaxy, cannot escape the powerful pull of gravity from these small spheres. While it is not yet proven, it is generally believed by astronomers that there is a black hole located at the direct center of our galaxy, and at the center of most galaxies. That means a black hole could be controlling the very path our solar system, Earth included, is traveling on.
Discovery and Composition
Discovery
The idea of a black hole is thought to have first originated from a British Reverend, John Mitchell, in 1783. Mitchell, and French scientist named Pierre-Simon Laplace, both believed that gravity could affect light, in addition to being able to affect matter. They figured that if a star was large enough (at least 501 times as large as our sun) , light would not be fast enough to escape the gravitational pull of the star. This speed required to escape from a gravitational pull is known as an escape velocity. The two scientists theorized that these massive stars could not be seen due to to the light not having a high enough escape velocity. However, this was all complete theory, with little-to-none actual evidence. Later, Albert Einstein released his General Theory of Relativity, which one could use to believe that black holes were real. Slowly, over the course of the next 50 years, scientists subsequently improved and elaborated on the idea of black holes. First after Einstein, was Karl Schwarzchild, a German scientist who theorized that black holes were perfectly spherical. Next, was Subrahmanyan Chandrasekhar, an Indian scientist. He came up with the idea that if a star got too massive, it would eventually collapse in on itself, and become a Neutron Star. A few years later, J.R. Oppenheimer, a member of the infamous Manhatten Projecft, came up with the maximum mass limit of a Neutron star. (3.2 solar masses). He believed that if the star got bigger than this, there would be nothing to work against the force of gravity, and the body would become a black hole. Several other scientists, including Roy Kerr and Stephen Hawking, expanded even more on the different ideas of black holes, particularly in the study of black holes that rotated. Finaly, in 1968, the term "black hole" was officially coined by John Wheeler. Shortly after,in 1972, actual evidence was found for black holes using X-Ray technology, making the fabled black holes no longer a myth, but an actual, existing spectral body.
Composition
The composition of a black hole is believed to be relatively simple. It has no actual matter on the inside, because every single thing that gets sucked into a black hole is transformed into nothing but gravitational energy. There are two main sections of a black hole, the Singularity, and the Event Horizon. The Singularity is the "core" of the black hole, a tiny point which all of the matter that is sucked into it becomes pure gravity. The Event Horizon is akin to the Earth's crust, in that it forms the boundary of a black hole. However, It is not a solid, just a boundary which marks the "point of no return." Once something, even light, passes into the Event Horizon, it cannot escape being sucked into the singularity. The Event Horizon is how scientists can "see" black holes, the light just suddenly stops, and it literaly appears that there is a hole in the middle of space.
Observing
One might imagine that black holes would be relatively difficult to observe, considering that they have a complete lack of light. However, there is actually a greater than normal amount of light surrounding a black hole. We can also occasionally see a quasar shoot away from black holes, emerging from near the black hole. We observe the effects and the surroundings of black holes through different types of telescopes, but whatever the type, they must be massive. The most common way we observe them is through arrays of massive radio telescopes that are scattered throughout the world, such as the Very Large Array. The black hole that we have come closest to actually observing is the event horizon of the black hole that is believed to be at the very center of our galaxy.
Relevant Matters of the Trivial Nature
Black holes are still objects that are largely shrouded in mystery, because of the fact that they are so far away, and so difficult to observe. In fact, almost everything that scientists think about black holes are just educated guesses. (To be fair though, almost all of science is just one big educated guess).
One particular field of interest in regards to the more fictional element of black holes are wormholes. Wormholes occur when black holes press "down" (directions are extremely subjective in the vast, empty plane of the universe) on the fabric of space-time so strongly, that two far away "fabrics" of space push together, creating an apparent link between the two. In theory, one could travel to a place thousands of light years away at a speed faster than that of the speed of light. According to Einstein's relativity equations, Schwarzschild wormholes (called so after Schwarzchild, who proposed the initial idea of them) can exist. However, wormholes are something that even if they were to exist, according to commonly held scientific beliefs it would be virtually impossible to use them for fast travel from one place in the galaxy to another, due to the fact that it would be impossible to escape the gravity of a black hole on one side, much less two black holes, in addition to the fact that wormholes are believed to be extremely unstable. Attempting to pass through a wormhole would be akin to attempting to dig through the center of our Earth with the goal of emerging on the opposite side, but with the center of the earth constantly closing in and out upon itself, and churning lava everywhere, one could probably get relatively near the core, but a person simply couldn't survive the journey through. [6] Unfortunately, wormholes seem to be a thing more of science fiction than an actual reality.
Another interesting, but extremely theoretical, subject related to black holes are white holes. The basic idea of a white hole is that instead of sucking everything in like a black hole does, a white hole is constantly ejecting matter, thus becoming the antithesis of a black hole. However, the idea of this has almost been completely disproven by popular science, in particular because of the fact that the principle of a white hole violates the second law of thermodynamics. [6]
Embedding diagram of the Schwarzschild wormhole geometry, with white and black holes.
Table of Contents
Black Holes
Black holes are small, yet amazingly powerful ethereal bodies in outer space. A black hole comes from the remains of a massive star collapsing in on its self, and when it does this, what was once an extremely large star, taking up space in the magnitude of several times larger than the Sun of our own Solar System, into a sphere that is roughly the size of a small town. The result of this massive amount of matter being compressed into a not so massive area of space creates a field of gravity that is so strong, that it sucks up everything that enters it. Even light, an energy that is heralded far and wide as being the fastest bit of matter in the galaxy, cannot escape the powerful pull of gravity from these small spheres. While it is not yet proven, it is generally believed by astronomers that there is a black hole located at the direct center of our galaxy, and at the center of most galaxies. That means a black hole could be controlling the very path our solar system, Earth included, is traveling on.
Discovery and Composition
Discovery
The idea of a black hole is thought to have first originated from a British Reverend, John Mitchell, in 1783. Mitchell, and French scientist named Pierre-Simon Laplace, both believed that gravity could affect light, in addition to being able to affect matter. They figured that if a star was large enough (at least 501 times as large as our sun) , light would not be fast enough to escape the gravitational pull of the star. This speed required to escape from a gravitational pull is known as an escape velocity. The two scientists theorized that these massive stars could not be seen due to to the light not having a high enough escape velocity. However, this was all complete theory, with little-to-none actual evidence. Later, Albert Einstein released his General Theory of Relativity, which one could use to believe that black holes were real. Slowly, over the course of the next 50 years, scientists subsequently improved and elaborated on the idea of black holes. First after Einstein, was Karl Schwarzchild, a German scientist who theorized that black holes were perfectly spherical. Next, was Subrahmanyan Chandrasekhar, an Indian scientist. He came up with the idea that if a star got too massive, it would eventually collapse in on itself, and become a Neutron Star. A few years later, J.R. Oppenheimer, a member of the infamous Manhatten Projecft, came up with the maximum mass limit of a Neutron star. (3.2 solar masses). He believed that if the star got bigger than this, there would be nothing to work against the force of gravity, and the body would become a black hole. Several other scientists, including Roy Kerr and Stephen Hawking, expanded even more on the different ideas of black holes, particularly in the study of black holes that rotated. Finaly, in 1968, the term "black hole" was officially coined by John Wheeler. Shortly after,in 1972, actual evidence was found for black holes using X-Ray technology, making the fabled black holes no longer a myth, but an actual, existing spectral body.
Composition
The composition of a black hole is believed to be relatively simple. It has no actual matter on the inside, because every single thing that gets sucked into a black hole is transformed into nothing but gravitational energy. There are two main sections of a black hole, the Singularity, and the Event Horizon. The Singularity is the "core" of the black hole, a tiny point which all of the matter that is sucked into it becomes pure gravity. The Event Horizon is akin to the Earth's crust, in that it forms the boundary of a black hole. However, It is not a solid, just a boundary which marks the "point of no return." Once something, even light, passes into the Event Horizon, it cannot escape being sucked into the singularity. The Event Horizon is how scientists can "see" black holes, the light just suddenly stops, and it literaly appears that there is a hole in the middle of space.
Observing
One might imagine that black holes would be relatively difficult to observe, considering that they have a complete lack of light. However, there is actually a greater than normal amount of light surrounding a black hole. We can also occasionally see a quasar shoot away from black holes, emerging from near the black hole. We observe the effects and the surroundings of black holes through different types of telescopes, but whatever the type, they must be massive. The most common way we observe them is through arrays of massive radio telescopes that are scattered throughout the world, such as the Very Large Array. The black hole that we have come closest to actually observing is the event horizon of the black hole that is believed to be at the very center of our galaxy.
Relevant Matters of the Trivial Nature
Black holes are still objects that are largely shrouded in mystery, because of the fact that they are so far away, and so difficult to observe. In fact, almost everything that scientists think about black holes are just educated guesses. (To be fair though, almost all of science is just one big educated guess).
One particular field of interest in regards to the more fictional element of black holes are wormholes. Wormholes occur when black holes press "down" (directions are extremely subjective in the vast, empty plane of the universe) on the fabric of space-time so strongly, that two far away "fabrics" of space push together, creating an apparent link between the two. In theory, one could travel to a place thousands of light years away at a speed faster than that of the speed of light. According to Einstein's relativity equations, Schwarzschild wormholes (called so after Schwarzchild, who proposed the initial idea of them) can exist. However, wormholes are something that even if they were to exist, according to commonly held scientific beliefs it would be virtually impossible to use them for fast travel from one place in the galaxy to another, due to the fact that it would be impossible to escape the gravity of a black hole on one side, much less two black holes, in addition to the fact that wormholes are believed to be extremely unstable. Attempting to pass through a wormhole would be akin to attempting to dig through the center of our Earth with the goal of emerging on the opposite side, but with the center of the earth constantly closing in and out upon itself, and churning lava everywhere, one could probably get relatively near the core, but a person simply couldn't survive the journey through. [6] Unfortunately, wormholes seem to be a thing more of science fiction than an actual reality.
Another interesting, but extremely theoretical, subject related to black holes are white holes. The basic idea of a white hole is that instead of sucking everything in like a black hole does, a white hole is constantly ejecting matter, thus becoming the antithesis of a black hole. However, the idea of this has almost been completely disproven by popular science, in particular because of the fact that the principle of a white hole violates the second law of thermodynamics. [6]
http://casa.colorado.edu/~ajsh/schww.html
References
1. http://hubblesite.org/explore_astronomy/black_holes/encyclopedia.html2. http://www.space.com/blackholes/
3. http://library.thinkquest.org/25715/discovery/index.htm
4. http://www.gsfc.nasa.gov/scienceques2002/20030516.html
5. http://curious.astro.cornell.edu/blackholes.php
6. http://casa.colorado.edu/~ajsh/schww.html